For example, in a pressurized water reactor (PWR), light water is used as a reactor coolant and a neutron moderator, high-temperature and high-pressure water which is not boiled throughout a core is sent to a steam generator to generate steam by heat exchange, and the steam is sent to a turbine power generator to generate power. In addition, the pressurized water reactor transfers heat at high-temperature and high-pressure primary cooling water to secondary cooling water by using the steam generator and generates steam in the secondary cooling water. In the steam generator, primary cooling water flows in a plurality of thin heat transfer tubes, heat is transferred to the secondary cooling water that flows outside to generate the steam, and a turbine is actuated by the steam to generate power.
In the steam generator, in a body having a hollow sealing shape, a tube bundle shroud is arranged with a predetermined distance from an inner wall surface, a plurality of heat transfer tubes having an inverse U shape are arranged in the tube bundle shroud, an end portion of each heat transfer tube is supported on a tube sheet, and an inlet bowl and an outlet bowl of the primary cooling water are formed at a lower end portion of a body. Further, in the body, an inlet of the secondary cooling water positioned at an upper side of the tube bundle shroud is installed in the body, a steam-water separator and a moisture separator are vertically arranged in parallel, and a steam outlet is installed at an upper side thereof.
Therefore, the primary cooling water is supplied to the plurality of heat transfer tubes from a cooling water pipe through the inlet bowl, while the secondary cooling water is supplied into the body from the inlet. Then, heat exchange is performed between the primary cooling water that flows in the plurality of heat transfer tubes and the secondary cooling water (cooled water) that is circulated in the body, and as a result, the secondary cooling water absorbs heat to generate the steam. In addition, moisture is removed from the generated steam by the steam-water separator, and the steam of which the moisture is removed by the moisture separator is discharged from a steam outlet, while the primary cooling water in which heat exchange is terminated is discharged from the outlet bowl.
In the steam generator, the plurality of heat transfer tubes installed in the body is supported by the plurality of tube supporting plates. In the tube supporting plates, the heat transfer tubes are inserted into a plurality of holes, and as a result, the plurality of heat transfer tubes is supported so as not to vibrate. In this case, the holes of the tube supporting plates are formed by performing a cutting process using a predetermined processing device, but thereafter, whether positions or inner-diameter sizes of the holes are appropriate needs to be examined.